Luminaire having a radial polarizing structure

ABSTRACT

Luminaire apparatus is provided for illuminating a specified area with light having improved contrast characteristics. Collimated light is provided from an illumination apparatus to a radial polarizer. The radial polarizer linearly polarizes and radially distributes the collimated light. The radially polarized light then passes through a refractor, which spreads the radially polarized light for illuminating a wider area than would be possible without the refractor.

United States Patent 1191 Howe et al.

[451 Oct. 14, 1975 LUNIINAIRE HAVING A RADIAL POLARIZING STRUCTURE [75] Inventors: James D. Howe, Rochester; Eugene C. Letter, Penfield, both of NY.

[73] Assignee: Bausch & Lomb Incorporated,

Rochester, NY.

22 Filed: May 28, 1974 21] Appl. No.: 473,857

[52] US. Cl 240/9.5; 240/41.4 R; 240/106 R; 240/106.1

[51] Int. Cl. F21V 9/14 [58] Field of Search 240/9.5, 41.4 R, 41.4 D, 240/106 R, 106.1

[56] References Cited UNITED STATES PATENTS 2,270,535 1/1942 Land et al 240/9.5

6/1956 Gefieken et al. 240/9.5 10/1967 Kruger 240/9.5

Primary Examiner-Samuel S. Matthews Assistant Examiner-Russell E. Adams, Jr.

Attorney, Agent, or Firm-Frank C. Parker; Harry C. Post, III

[57] ABSTRACT Luminaire apparatus is provided for illuminating a specified area with light having improved contrast characteristics. Collimated light is provided from an illumination apparatus to a radial polarizer. The radial polarizer linearly polarizes and radially distributes the collimated light. The radially polarized light then passes through a refractor, which spreads the radially polarized light for illuminating a wider area than would be possible without the refractor.

11 Claims, 5 Drawing Figures US. Patent Oct. 14, 1975 Sheet20f2 3,912,921

LUMINAIRE HAVING A RADIAL POLARIZING STRUCTURE BACKGROUND SUMMARY OF THE INVENTION Since electrical lighting has been used to illuminate the work area of an individual employed within a building, the lighting industry has been devising methods to provide improved contrasts at the task surface and thus better visibility. As stated at p. 32 in Progress in Solving Veiling Reflections, Lighting Design & Application, 3l34, May, 1973, basically three methods are used. These methods are:

A. increasing the amount of illumination at the work area;

B. controlling the distribution of light; and

C. polarizing the light.

A typical example of Method A is an arrangement of a series of fluorescent lamps extending in a row or rows over the work area. A device to control the distribution of light, Method B, is a refractor lighting panel which is positioned between a fluorescent lamp and the work area to diffuse the light over the work area either evenly or in a preferred direction. Examples of such refractor lighting panels are illustrated in U.S. Pat. No. 3,794,829 issued to I. G. Taltavull. The polarization of light, Method C, is normally obtained by positioning a polarizing panel between a fluorescent lamp and the work area. Some examples of such devices are given by A. M. Marks et al. in US. Pat. No. 3,024,701 and M. Kahn et al. in US. Pat. No. 3,124,639.

In view of the energy crisis facing the world one of the design criteria for lighting must be the lighting efficiency of the luminaires used. When reviewing Methods A-C in view of this design criteria, we have discovered a light modifying device for conserving a substantial amount of energy in luminaires. The light modifier converts substantially collimated light to radially polarized and refracted light by using a conical member a refractor and a linear polarizer material disposed between the conical member and refractor. Radially polarized light is defined, for purposes of this application, as light that is linearly polarized and radially distributed. Our radial polarizing and refracting light modifier permits a substantial part of the light to pass therethrough and diminish the veiling reflections from a task surface. Accordingly, when using our light modifier the amount of contrast at the task surface may be maintained with an amount of light less than that used in conventional luminaires. Further, we conserve energy by using a highly efficient light source to generate the substantially collimated light, as with a high intensity discharge lamp positioned within a parabolic reflector.

BRIEF DESCRIPTION OF THE DRAWINGS Objects and advantages of the invention will become apparent upon reading the following description and upon reference to the drawings, in which like reference numerals refer to like elements in the various views:

FIG. 1 is an elevational view, partly in section, of an embodiment of our present invention with a perspective view of the illuminated area.

FIG. 2 is an enlarged plan view of an array of light modifying elements using our present invention.

FIG. 3 is an elevational sectional view taken along lines 3-3 of the embodiment illustrated by FIG. 2.

FIG. 4 is an elevational sectional view of a single light modifying element taken along lines 4-4 of the embodiment illustrated by FIG. 2.

FIG. 5 is an exploded elevational view of a portion of the polarizing material used in the embodiment illustrated in FIGS. 2-4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As best seen in FIG. I, a luminaire has a high intensity discharge lamp 12 disposed within a parabolic reflector 14 and light modifier 16 positioned to receive light emitted from lamp 12. When lamp 12 is activated, light rays, represented by typical light ray 18, are reflected from reflector 14 to produce substantially collimated light rays, represented by typical substantially collimated light ray 20. Although collimated light ray 20 is illustrated with 0 deflection, collimated light ray 20 may vary as much as One factor determining the amount of deflection of collimated light ray is the size of reflector 14 relative to the size of lamp 12. That is, there will be less deflection of collimated light ray 20 as reflector 14 increases in size until lamp 12 seems to become relatively a point source of light. Another factor determining the amount of deflection is the shape of reflector 14, which may be slightly deviated from a parabolic shape, such as with a slightly faceted parabolic reflector.

Light modifier 16 is constructed from an array of elements 22 with each element 22 having an axis of symmetry 24 with a description of each element 22 being explained in greater detail hereinafter. Normally, axis of symmetry 24 of each element 22 is positioned substantially parallel to the 0 deflection of substantially collimated light ray 20 for better efficiency of array 16''. As substantially collimated light ray 20 passes through each radial polarizer-refractor element 22, collimated light ray 20 is modified by each element 22 to provide radially polarized light rays 26 radially spread over an area 28. Each modified light ray 26 within illuminated area 28 is linearly polarized and distributed radially of axis of symmetry 24, as illustrated by radial arrows 30.

The construction of each element 22 of light modifying array 16 is best seen in FIGS. 25. When a single element 22 is being constructed, single element 22 will have axis of symmetry 24 and be defined by a base surface 32, spherical surface 34 facing outwardly of substantially collimated light ray 20 and side surfaces 36, as seen in FIG. 4. However, it is not necessary to have side surfaces 36 for each element 22 when an array is being formed. As shown in FIG. 3, side surfaces 36 exist only at the edges of array 16.

Radially polarized light rays 26 are obtained from collimated light rays 20 by our using a conical member 38 within each element 22 and linear polarizer 46. Conical member 38 is defined by the base being base surface 32 of each element 22, cone sides 40 tapering from base 32 directed to a point 42 lying on axis of symmetry 24 and scalloped edges 44. The scalloped edges 44 of each conical member 38 are formed by a multiple number of planes lying parallel to line of symmetry 24. We prefer the number of edges 44 for each conical member 38 to be six, forming a hexagon when viewed in plan, for better nesting of conical members 38 within array 16. When conical members 38 are positioned in array 16, the edges 44 of one conical member 38 are contiguous with edges 44 of other conical members 38. Linear polarizer 46 is disposed between cone sides 40 and the remainder of each element 22, the remainder acting as a refractor 48 to radially spread the radially polarized light. As best seen in FIG. 5, polarizer 46 is a multilayer material using optical interference from alternative high (N,,) and low (N index of refraction layers to control the ratio of reflected light 20r to transmitted light 20p. A polarizer of this type has been described in U.S. Pat. No. 2,403,731, issued to S. M. MacNeille for a Beam Splitter. I

In our light modifier, we prefer tapering cone sides 42 so that the angle between axis of symmetry 24 and each cone side 40 is substantially 45. One reason is that reflected light 20r is directed toward opposed cone side 40 and back into reflector 14. However, a return of reflected light 20r to the source of light may effect the efficiency of total light output from lamp 12; therefore, this angle may be varied by as much as (i The efficiency of the total light output may also be effected by providing an optical retarder between base surface 32 of each element 22 and lamp 12. Another reason is that this 45 angle may be approximated as the angle of incidence in the formulas given hereinafter and satisfactory results obtainable.

In constructing the light modifier, the materials used are selected partly because of their index of refraction. The general design relationship between the index of refraction of the materials used in cone 38, each layer of multilayer polarizer 46 and refractor 48 and the relationship between the index of refraction of the materials used in each layer of polarizer 46, the wavelength of light to be polarized and the thickness of each layer of polarizer 16 are explained by MacNeille. We use the following formulas to show these relationships:

layer in po- Some materials useable in cone 38 may be a glass or plastic having an index of refraction from 1.45 to 1.80. Materials used in constructing refractor 48 may also be a nonbirefringent glass or plastic having an index of refraction from 1.40 to 2.0. Some examples of materials useable in the multilayer polarizing arrangement are set forth in the following table:

The materials of the polarizers may be used in a single stack or multiple stacks of multilayers for polarization of different light spectrum. Although FIG. 5 shows a single stack of 7 layers, a single stack for use in the visible light spectrum of 13 layers of alternating high (ZnS) and then low (Na AlF index materials with an optical thickness of A design wavelength, conical member 38 having an index of 1.58, refractor 48 having an index of 1.49 and the angle of incidence being 45 may be constructed. Another example of a single stack dehaving an optical thickness of A design wavelength, 1

layer of low (Na AlF index materials having an optical thickness of 1.16 of A design wavelength and 5 layers of alternating high (ZnS) and then low (Na Allindex materials having an optical thickness 1.33 of A design wavelength conical member 38 having an index of 1.58, refractor 48 having an index of 1.49 and the angle of incidence being 45.

We claim: 1. Luminaire apparatus, comprising: illumination means for providing substantially collimated light; radial polarizer means for linearly polarizing and radially distributing the collimated light having an axis of symmetry; and refractor means for radially spreading the radially polarized light having an axis of symmetry, the axis of said refractor means being disposed substantially coincident with the axis of said polarizer means. 2. The apparatus of claim 1, wherein said illumina- 40 tion means include:

a high intensity discharge lamp for providing light;

and

a parabolic reflector for collimating the light from the lamp.

3. The apparatus of claim 1, wherein said radial polarizer means includes:

at least one conical member having sides tapering toward a point on the axis of symmetry of said radial polarizer means with the axis and sides directed outwardly of the illumination means; and

a multilayer optical interference material for linearly polarizing the collimated light disposed between N Material ZnS Ti0 CeO Zr0= Typical Index 2.35 2.35 2.30 2.05

N Material Na Al F Na;,AlF., MgF SiO Certain Glasses Typical Index 1.231.35 1.38 1.46 1.49

array of conical and spherical members.

9. A light modifier for radial polarization and dispersion of collimated light, comprising:

6. The apparatus of claim 5, wherein said refractor means includes a spherical member for each conical member.

7. Lighting apparatus, comprising:

a high intensity discharge lamp for providing light;

a parabolic reflector for substantially collimating the light from the lamp;

a plurality of radial polarizing conical members for linearly polarizing and radially distributing the collimated light, each conical member having an axis of symmetry and sides tapering toward a point on the axis and a multilayered optical interference material disposed adjacent the tapering sides of each conical member; and

at least one radial polarizing conical member for lin early polarizing and radially distributing the collimated light, each conical member having an axis of symmetry and sides tapering toward a point on the axis and a multilayered optical interference material disposed adjacent the tapering sides of each conical member; and

at least one spherical retracting member for radially spreading the radially polarized light, each refracting member having an axis of symmetry disposed coincidently with a corresponding conical member axis.

10. The light modifier of claim 9, wherein each conical member is defined by a cone intersected by six planes symmetrically disposed about the axis of the cone, the planes of one conical member being contiguous with planes of other conical members to form an array of conical and spherical members.

11. The light modifier of claim 9, wherein each conical member and multilayered material is disposed within the spherical member having the coincident axis.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION q PATENT NO. 3,912,921

DATED October l t, 1975 INVENTOR(S) James D. Howe and Eugene C. Letter It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, lil le l, change "BACKGROUND SUMMARY OF THE INVENTION" CO BACKGROUND & SUMMARY OF THE INVENTION.

1 Column 2, line 63, change "to be six" to --to be six (6)--.

Column 3, line 18, change "(i5)" to -plus orminus five degrees (i5)-'-.

Column line 40, change "include" to -includes--.

- Signed and Sealed this Twenty-third Day of November 1976 a [SEALl' I Arrest:

I RUTH C. MASON C. MARSHALL DANN AIM-fling Officer Commissioner of Parents and Trademarks 

1. Luminaire apparatus, comprising: illumination means for providing substantially collimated light; radial polarizer means for linearly polarizing and radially distributing the collimated light having an axis of symmetry; and refractor means for radially spreading the radially polarized light having an axis of symmetry, the axis of said refractor means being disposed substantially coincident with the axis of said polarizer means.
 2. The apparatus of claim 1, wherein said illumination means include: a high intensity discharge lamp for providing light; and a parabolic reflector for collimating the light from the lamp.
 3. The apparatus of claim 1, wherein said radial polarizer means includes: at least one conical member having sides tapering toward a point on the axis of symmetry of said radial polarizer means with the axis and sides directed outwardly of the illumination means; and a multilayer optical interference material for linearly polarizing the collimated light disposed between the tapering sides of said conical member and said refractor means.
 4. The apparatus of claim 3, wherein each conical member is defined by a cone intersected by multiple planes symmetrically disposed about the axis of the cone.
 5. The apparatus of claim 4, wherein the multiple planes number six and planes of one conical member are contiguous with planes of other conical members to form an array of conical members for creating a lighting panel to radially polarize the collimated light.
 6. The apparatus of claim 5, wherein said refractor means includes a spherical member for each conical member.
 7. Lighting apparatus, comprising: a high intensity discharge lamp for providing light; a parabolic reflector for substantially collimating the light from the lamp; a plurality of radial polarizing conical members for linearly polarizing and radially distributing the collimated light, each conical member having an axis of symmetry and sides tapering toward a point on the axis and a multilayered optical interference material disposed adjacent the tapering sides of each conical member; and a plurality of spherical refracting members for radially spreading the radially polarized light, each refractor member having an axis of symmetry disposed substantially coincidently with a corresponding conical member axis and each conical member and multilayered material being disposed within the spherical member having the coincident axis.
 8. The lighting apparatus of claim 7, wherein each conical member is defined by a cone intersected by six planes symmetrically disposed about the axis of the cone, the planes of one conical member being contiguous with planes of other conical members to form an array of conical and spherical members.
 9. A light modifier for radial polarization and dispersion of collimated light, comprising: at least one rAdial polarizing conical member for linearly polarizing and radially distributing the collimated light, each conical member having an axis of symmetry and sides tapering toward a point on the axis and a multilayered optical interference material disposed adjacent the tapering sides of each conical member; and at least one spherical refracting member for radially spreading the radially polarized light, each refracting member having an axis of symmetry disposed coincidently with a corresponding conical member axis.
 10. The light modifier of claim 9, wherein each conical member is defined by a cone intersected by six planes symmetrically disposed about the axis of the cone, the planes of one conical member being contiguous with planes of other conical members to form an array of conical and spherical members.
 11. The light modifier of claim 9, wherein each conical member and multilayered material is disposed within the spherical member having the coincident axis. 